The present invention relates to an optical free space interconnect of circuitry. Particularly, the present invention concerns optical interconnection employed in computers.
One of the current approaches to increasing computational and control power is to link multiple low cost, distributed processors together. In this manner, the cost associated with a single processor capable of the similar computational efficiency may be avoided. Currently the distributed processing is achieved by employing high-speed data links using conventional wire and connector technology, referred to herein as “hardwired technology”. Specifically, the high-speed data links facilitate data communication between processor nodes and other dedicated component-to-component and/or board-to-board applications as processor speeds increase. As processor speeds increase, however, the present data-links will result in data transfer bottlenecks, due to the limited data transfer rate the same may provide. Moreover, data link reliability may be compromised as the number of wires employed in the data link increases.
To improve the operational characteristics of the aforementioned data links, advancements in optical communication systems have been employed to replace the conventional the hardwired technology. A well-known example includes the replacement of conventional copper wires used for telephony with optical dielectric wave guides commonly know as optical fibers. This has generated a need for improvement methodologies to interconnect the optical fibers together or with other optical devices such as light sources, light detectors, and the like. To that end, the prior art is replete with improved techniques for interconnecting optical components.
U.S. Pat. No. 4,057,319 to Ash et al. discloses such a technique. Specifically, the patent to Ash et al. discloses an optical system in which individual connections are made involving the passage of light between a specific device in one array of optical devices and a specific device in another array of optical devices via a phase hologram plate of the transmission type fixed relative to each array.
U.S. Pat. No. 5,140,657 to Thylen discloses a device for optically coupling an optical fiber, forming part of an optical communication system, to an optical semiconductor laser amplifier. Specifically, the semiconductor laser amplifier has an input facet and an output facet, and the optical fiber has an end surface arranged opposite to at least one of the facets. A diffraction optics element is disposed between the end surface of the fiber and the surface of the facet in order to adapt the nearfield of the fiber end to the nearfield of the facet surface while filtering the same to reduce spontaneous emission noise. The diffraction optics element is described as being a phase hologram.
U.S. Pat. No. 6,072,579 to Funato discloses an optical pickup apparatus that includes first and second light sources that selectively emit one of first and second light beams. The first and second light beams are different in wavelength and are suitable for accessing first and second optical disks respectively. A coupling lens converts a corresponding one of the first and second light beams into a collimated beam. An objective lens forms a light spot on a corresponding one of the first and second optical disks by focusing the collimated beam. A holographic optical element receives a reflection beam of the light spot from one of the first and second optical disks and provides holographic effects on the reflection beam so as to diffract the reflection beam in predetermined diffracting directions depending on the wavelength of the reflection beam. A photo detector receives the reflection beam from the holographic optical element at light receiving areas and outputs signals indicative of respective intensities of the received reflection beam at the light receiving areas, so that a focusing error signal and a tracking error signal are generated based on the signals. A drawback with the aforementioned optical interconnect systems is that each coupling device requires precise alignment of the optical elements to achieve efficient coupling of optical energy.
What is needed, therefore, is an optical coupling technique that decreases the alignment tolerances of the various optical devices between which optical energy is coupled.